Radio communication systems conforming to 3rd Generation Partnership Project (3GPP) standards such as 3G and Long Term Evolution (LTE) include a mechanism (access control) that prevents multiple user devices from accessing a network at the same time to reduce the network load.
First, Access Class Barring (ACB) is an access control scheme that makes it possible to prevent access from user devices to a network at a specified probability by including a flag indicating prevention of access to the network or a barring rate in broadcast information for reporting various types of information from the network to the user devices. Using ACB makes it possible to restrict calls from user devices to a network. However, with ACB, except for, for example, an emergency call, it is not possible to control access according to the types of services (see, for example, Non-Patent Document 1).
Next, Service Specific Access Control (SSAC) makes it possible to report different barring rates for voice and video calls in an IP Multimedia core network Subsystem (IMS) to prevent voice and video calls at probabilities corresponding to the barring rates. SSAC makes it possible to restrict access to a network handling the IMS and to reduce the load of the network (see, for example, Non-Patent Document 1).
Next, Access Class for CSFB makes it possible to report a barring rate for calls according to a circuit switched fallback (CSFB) scheme, and thereby makes it possible to prevent calls according to the CSFB scheme at a probability corresponding to the barring rate. When a user device in an LTE network is to use a service such as a voice call provided by a circuit switched (CS) domain, CSFB enables the user device to transition from the LTE network not supporting the CS domain to a Universal Mobile Telecommunications System (UMTS) network or a Global System for Mobile Communications (GSM: registered trademark) network supporting the CS domain, and thereby enables the user device to make a voice call. Access Class for CSFB makes it possible to restrict access to a network supporting the CS domain and to reduce the load of the network (see, for example, Non-Patent Document 1).
Also, Application specific Congestion control for Data Communication (ACDC) is specified by 3GPP Release 13 (see, for example, Non-Patent Document 1). ACDC is an access control scheme that enables access control for each application installed in a user device. Independent of an access control scheme such as IMS or CSFB, ACDC makes it possible to allow communications performed by an application specified by broadcast information and to prevent communications performed by an application specified by broadcast information at a specified probability.
Specifically, according to ACDC, information called ACDC categories for categorizing specific applications is stored in a user device. The network reports barring rates associated with the ACDC categories to the user device via broadcast information. This makes it possible to restrict communications performed by specific applications or to allow only communications performed by specific applications.